Another "Hold Open" question.

[ithacaartist]

David, WWII era mags are very often the aluminum-bottomed, milled, heavy-duty ones made by Haenel. If this is the case, they are generally reputed to work and hold up very well, and have great springs, as well. If it's a somewhat earlier, shell-constructed jobber, a check of its notch should be done becasuse it strikes me that they would wear more, when compared to the later ones. Get a Mec-gar and see if you have better results. The hold-open may have rounded corner-itis. or the mag is riding low at a point that its follower button will engage the hold-open enough to lock the toggle back when the button is at the top and helping, but not securely enough that the hold-open has enough of a "bite" without that support and consequently slip when the mag is yanked. A little vertical play in a mag is within expectations, but if it is excessive, all mags will ride low enough to cause the problem, and the mag catch would then be the culprit. Firing the pistol while supporting the mag from below is one rough test for this problem.

Depending on how long this has been going on, the edge of the hold-open should be checked for sharpness to make sure it's not a compound concert of quirks put together.

The Erma KGP series Hold-opens work the same way. One was misbehaving in exactly this same way. I dressed the corner of the hold-open, but no improvement. A new hold-open cured it completely. The earlier, mostly-zinc Erma toggle guns depend on a booger at the back of the mag follower, which sticks up enough when the mag is empty to catch the breech block and hold it back. I appreciate that they signal the empty mag, but the action snaps shut like a trap when the empty mag is removed...and you'd better not have any skin near it during the three-handed chore of taking out the mag after the last shot.

Let's see what others may advise...